Injector question

> Guys-
> My engine has about 195,000 miles on it - presumably original injectors.
> How can you tell if its time to have them professionally
> rebuilt/cleaned/whatever? My car is running rich and I have replaced
> the 02 sensor, coolant temp sensor, no vac leaks, no codes, plugs and
> cap/rotor have 15k miles, MAF has been tested on another car. Somebody
> suggested maybe injectors aren't spraying a good pattern and may need
> service. Seems to make sense, potentially.
Just how rich are we talking here? In theory, when in closed loop operation
the ECU will adjust mixture using O2 sensor to "perfect" stoich. A number of
people have had trouble with fuel pressure regulator - if the pressure is
too high then injectors may be putting in too much even at ECU's minimum
allowed duty cycle. Something to check with VAG-COM? How do the plugs look?
You could run some injector cleaner through, just for grins. I would imagine
that any spray pattern variances would result in per-cylinder non-optimal
running but the ECU (again, in theory) will even everything out since
there's only the one O2 sensor.
Henry